The economic pressures being experienced in the agricultural field as a result of rising costs that cannot be recovered through increased selling prices have led those charged with the responsibility of running farming operations to seek methods for curtailing expenses to the extent possible. The pressure to control costs has given rise to attempts to increase the degree to which framing operations can be automated so as to reduce labor costs. In the area of animal husbandry, for example in dairy farming, there has been an extensive effort to increase the number of animals that can be cared for by an individual, through the use of automated milking devices, feed-conveying systems, and similar expedients. Also with respect to dairy farming, extensive effort has been devoted to increasing revenues by maximizing milk production, among other things, by making sure that the animals have an ample supply of food available for their use at all times.
In the past, a variety of systems have been used to automatically distribute feed to milk cows. Such systems typically involve conveyor systems for moving feed from a storage area to some type of feeding trough accessible to the cows. In some case, the systems include ways in which to detect the availability of feed to the animals, and to activate or inactivate the transfer system, depending on the nature of the information supplied by the detector.
One such system depends upon a spring-positioned, pivotable paddle mounted in the feed station supply hopper. When the paddle is positioned by its spring in an extended position away from an associated switch, the switch is free to activate a feed-supply auger until the hopper fills to the point at which the weight of the feed forces the paddle to oppose the force of the spring, folding the paddle back against the hopper wall where it contacts and throws the switch, turning off the supply auger. When the feed drops below the level of the paddle, the latter is again forced by its spring away from the switch, reactivating the auger. While the system is simple in concept, it suffers from the fact that the feed in the hopper has a tendency to accumulate behind the paddle with the passage of time, eventually, preventing pivoting of the paddle, and therefore, its contact with the switch.
Another system sometimes used depends upon feed detection by a photoelectric cell positioned in a translucent section of the feed hopper. When feed within the hopper drops below the level of the cell, the feed auger is activated, causing feed to flow into the hopper until the feed level rises to the point at which it can be detected by the cell, resulting in deactivation of the auger. Among other things, however, the system suffers from the fact that adventitious light has a tendency to enter the translucent section from above and below the photocell, producing the false readings, thus interfering with proper functioning of the cell. In addition, the light source on which the photocell depends has a relatively high failure rate, rendering the system inoperable until a light source problem is noted and corrected.
Systems have also been developed which depend on light emitting diodes, and counterpart detectors, mounted essentially flush in the wall of the feed hopper system, which detect the presence or absence of feed in the hopper. However, the flush-mounted LED detectors have a tendency to be covered and, therefore, "blinded" by the accumulation of feed along the wall on which the detectors are mounted, resulting in failure of the system.